Final answer:
The probability that the ball lands in a green slot at most once in 20 spins is approximately 0.891.
Step-by-step explanation:
To find the probability that the ball lands in a green slot at most once in 20 spins, we need to calculate the probability of landing in a green slot 0 or 1 times.
First, we can calculate the probability of landing in a green slot 0 times. The probability of not landing in a green slot in one spin is 36/38, so the probability of not landing in a green slot in 20 spins is (36/38)^20.
Next, we can calculate the probability of landing in a green slot exactly once. The probability of landing in a green slot in one spin is 2/38, so the probability of landing in a green slot once in 20 spins is (2/38) * (36/38)^19 * C(20,1), where C(20,1) represents the number of ways to choose 1 spin out of 20.
Finally, we add these two probabilities together to get the probability of landing in a green slot at most once. Using a TI-83, TI-83 Plus, or TI-84 calculator, we can calculate this probability to be approximately 0.891.